Refrigerating truck



13, 193. A Q SMHTH REFRIGERATING TRUCK FiIed Dec. 20. 1927 vWm ATTORNY Pii'tent d-May" 13, mo

UNITED STATES PATENT orrice f ALBERT ,c. sums, or wm'rnnor, mnssnonusmrs, ASSIGNOR iro WILLIAM F. ramp;

on BosroN, mn'ssncnpsn rrs REFRIGERATING- 'rnucx Application filed December 20,1!22'3'. Seriatlh. 241,4a

necessary to keep the ice cream frozen during transportation and for this purpose it is} the usual practice to pack the ice. cream in cans and to pack these cans in a mass-of chopped ice held in the truck body. The ice wastes 3 rapidly in summer temperatures, and on long hauls in hot weather there is great danger of the ice cream becoming soft and unsaleable.

. Furthermore, this practice involves the ham 2o dling and transportation of a heavy unprofitable load, namely, the ice. F

With a view to. overcoming these difliculties it has been proposed heretofore to equip a truck with a refrigerating plant. But the operation of a refrigerating plant from the power plant of a truck in a manner which is reasonably economical of power, has the requisite degree of reliability,-and does not involve excessive first cost and operating expense, presentsvery difficult practical problems. The problem. is complicated by the fact that the powerfor driving the-pump or compressor of the refrigerating systemvaries from zero to very high values, whereas it is impractical to drive the pump or compressor at suchyariable speeds, the nearer constant the speed of the compressor can be kept, the better from a refrigerating standpoint.

To devise a satisfactory solution for these problems forms the chief object of this invention. The nature of the invention will be readily understood from the ifollowing description when read in connctio with the accompany- '4 ing drawings, and the novel features will be particularly pointed out in the appended -claims.

In the drawings,

Figure-1 is a side elevation showinga truck equipped with refrigerating apparatus embodying this inv ention, some parts of the apparatus being shown diagrammatically; an

- Fig. 2 is a plan view, partly in cross-sew I Y tion, showing diagrammatically the organization of the system. M

-While the invention may be applied to any suitable type of truck, the truck shown is of a common construction so far as the chassis and the features of general organi- 3 zation are concerned, with the exceptions to be hereinafter described. It includes a power plant consisting of an engine 1 of the internal combustion type mounted under the hoodt2 and driving connections to the rear wheels,

these connections including a transmiss on mechanism, parts of' which are mounted in the transmission casing 3. Preferably a truck is used to which apower take-off. can be. ap-

plied to the transmission. That is, an attach ment is secured 'to the itransmission casing, this attachment including-a shaft 4 carrying a gear which meshes with a gear in the transmission so that this shaft is permanently connected with the power plant of the truck and power can be taken off the shaft 4 for any purpose. Such constructions are commonly used in dump trucks.

The body is mounted on the chassis and is provided with a refrigerating chamber 6' which is well insulated and may be of any form suited to the requirements of the material to be handled. Doors 6- open into opposite sides of the chamber and permit the introduction and removal of the cans or packages of ice cream, or the like. This truck is preferably, although not necessarily, is of the compression type, designed to use a refrigerant such, for example, as methyl chloride or sulphur dioxid. The system includes expan- I together so that they, form, in effect, a single coil. Pipe connections lead the expanded equipped with a refrigerating system which gas to a compressor or pump 8 from which the refrigerant is discharged into a condenser 9. The compressed and liquefied refrigerant collects in a chamber at the lower part of the condenser and subsequently flows through an chine compartment todistinguish it from the refrigerating compartment 6, the former compartment being preferably located transverse- 'lyin the forward part of the truck body.

Doors 13 and 14 are provided to open or close I 5 the opposite ends of the compartment 12, each of these doors preferably being of a shutter or louvre type so that they alford a free circulation of air through the compartment 12 from one end thereof to the other even when they 2'0 are closed. Such a circulation of air is utilized to cool the condenser 9, and for the purpose of creating a sufficient flow of air, a fan 15, Fig. 2, is located immediately behind the condenser and is mounted on the compressor shaft 16. i

As above indicated, an important problem in the operation of a system'of this character is'to drive the compressor 8 at a fairly constant speed, or at least without excessive speed variation, from the power plant of the truck, the speed of which'varies anywhere from a few revolutions per minute to 2,000 B. P. M., or even more. I have satisfactorily solved this-problem by drivin the compressor 8 from an electricv motor 1 and supplying the current for this motor from a direct 1 current generator 18 which preferably is mounted on the chassis of the truck and is directly connected with the power take-off 40 shaft 4 previously referred to. With this arrangement the generator armature will re- .volve' at a speed equal, or at least proportionate, to the speed of the truck engine. Consequently, the voltage delivered by the generator will vary widely.-

In order to reduce variations in the voltage impressed on the motor 17 I prefer to use a voltage regulator in connection with the direct current generator, and any suitable automaticregulator may be used for this purpose.

The regulator indicated in the drawings is of the well known type in which a series of carbon plates are arranged to be pressed more or less together.

55 Referring to Fig. 2 it will be observed that a series of carbon plates 20 of the voltage re ulator 21 are connected directly in series with the field of the generator 18, while the solenoid 22 of the regulator is connected 1 across the terminals of the generator. This solenoid acts on a core which'is connectedwith the plates 20, the arrangement belng such that the plates are presesd together and offer a minimum of resistance when the gen- Fj erat'or voltage is1ow-and are gradually allowed to separate to increase the resistance as ization results in reducing very materially the variations in voltage impressed on the motor, and consequently reduces variations in motor speed and therefore in the compressor speed. Assuming, for example, that the normal potential of the generator 18 is- 110 volts, it will not run substantially over this figure, except in case of accident, even at maximum truck speeds. At idling speeds the potential may drop to in the neighborhood of 7 5 volts.

This will mean some variation in the motor speed, but the motor preferably is connected with the compressor through a reduction gearing. As shown, the motor 17 carries a pinion 23 driving a'relatively large gear 24 on the compressor shaft 16. The compressor speed'therefore is always very much lower than the motor speed, and consequently variations in the motor speed will produce much smaller variations in the speed of the compressor. tains the compressor speed within entirely satisfactory limits.

The circuit connections between the generator 18. and the motor 17 will be clear from an inspection of the wiring diagram in Fig. 2. In order td protect the motor in the event that the generator voltage rises to excessive values,a high voltage circuit breaker is included in the motor circuit, this piece of apparatus comprising a solenoid 25 connected Such an arrangement mainacross the generator terminals and arranged ;to open a switch 26 when current exceeding a predetermined value flows through it, as will be readily understood by those skilled in this art. I

Provision is also made forautomatically controlling the operation of the compressor in accordance with the temperature in the refrigerating chamber 6. For this purpose a thermostat, indicated diagrammatically at 28, Fig. 2, is mounted in the chamber 6 and is connected through a double throw switch 30 with a solenoid 31 controlling a switch 32. Normally the switch 30 is thrown down, and is in engagement with the contacts 29, and so longas the temperature in the refrigerating chamber 6 remains below the value for which the thermostat 28 is set, the circuit through the thermostat and the solenoid 31 s Preferably the switch 32 .is arranged to con-\ ne ct the'resistance 33 into the motor circuitbefore cuttingout the motor entirely, so that excessive sparking o "the contacts will be avoided; In closing" this switch, also, the resistance is first cut into the circuit so that the full potential of the generatoris not immediately impressed on the motor. I

I It is sometimes necessary to leave a loaded t ck in a garage overnight, or for some sub- ,stantial' period, during which-the powerv plant of the truck will be idle. In order to operate the refrigerating systems under these conditions, an alternating current motor 35 is mounted in the machine chamber 12 beside the direct current motor 17 and is provided with a pinion 36 to mesh with anddrive the compressor gear 24. An alternating current motor is used for this purpose,-sincealternating current is used almost universally in lighting systems. Preferably, also, the circuit connections are such, as shown in Fig. 2, that the generator 18 can be disconnected from" the-motor circuit by throwingthe switch 42 down. into engagement with the contacts 43 which lead to a socket 44into which, any

suitable source of direct current canbev plugged,.it being understood that normally the switch 42 engages the upper contacts 45.

The D. C. motor, therefpre, can be operated from an outside source of current. The circuit connections for. the A. '0. motor include an automatic starting switch 37, Fig. 2,

' of a usual type, sockets or connectors 38 and alternating current, and contacts 40, Fig. 2, .for connecting the thermostat 28 in the motor circuit simply by throwing the switch 30 up-. ward. This arrrngement permits the thermostat 38 to control automatically the oper- Y ration of thejA. C. motor 35 in'accordan'ce "with the changes of temperature in the e .frigerating chamber '6.

, It has been demonstrated in practice-that this inventionefl'fectually solves the difiicul't'y 20f operating the refrigerating system from 1' 'athe power plant of a truck. A truck equipped with apparatus such as that shown not only --keeps its load cool-inweather and under conditions which would rove exceedingly troublesome for a truck epending upon ice, but it also avoids the handling and hauling eof-the ice. The radius of operations of the sltruck is widened, and it can be used for a greater variety of service than a truck in whichice is depended upon. The first cost as 'well as the operating expense of an installation of this character are within reasonablellimits, its efliciency, is satisfactory, and

nary driver'with entire confidence that the sys'temwill operate-satisfactorily and that t the driver will have no occasion to touch it.

s Having thus described my invention, what I deslre to claim as-newis:

.generator,'-positi-ve driving connections be- 39 in parallel with the motor and adapted to be connected to any convenient source efplying said motor with. current from said the chassis of the truck and directly connected it possesses a high degree of reliability so that it can .be placed in the hands of the ordi- While a typical organization embod ing this invention has been herein; shown an described, it be evident that the invention may-be embodied in other forms without departingfrom the-spirit or scope thereof. For example, the generator can be mounted and driven in other ways than shown,-although v the arrangement illustrated has certain advantages.

- 1. a motor truck hayingv a power-plant adapted to drive the same, the combination of a refrigerating system mounted in the truck and including a compressor, an electric enerator driven, from said power plant, an e ectric motor, driving-connections be% tween said motor and said compressor, and. circuit connections for supplying said motor with current from said generator. 2. In a motor truck having a power plant adapted to drive the same, the combination of a refrigerating system mounted in the truck'and including a compressor, an electric t eensaid ele e'tric generator and said power p ant,=an electric motor, driving connections between said otor and said compres or, and circuit connec ions for supplyingsai motor with current from said generator.-

3. In a motor truck having-a power plant adaptedto drive the sameythe combination of 'a refrigerating systenr mounted in the 'truck and including acompressor, an electric generator driven from said power plant, an automatic voltage regulator for said generator, an electric motor, circuit connections forsupplying said motor with current from Said generatoigfland driving connections'between said motor and said compressor.

4. Ina-motor truck havinga power plant adapted to drive the same, the combination of a refrigerating system in the truck,"said 1 system including'a' compressor, a direct current electric generator mounted on the chassis of; the truk, positive driving connections between sai generator and said power plant,

an electric motor, circuit connections for supgenerator, an automatic voltage regulator 5. Ina motor truck having apower plant adapted to drive the same and a transmission mechanism'actuated thereby and including a power take-off shaft, the-combination of a direct current electric generator mounted on 9 to said shaft, a retrigerator system "in said. L5 truck, said system including a compressor, an electric motor connect (1 with said comprcssor to'drive the same, circuit connections for supplying said motor witlrcurrentfrom; lab

for said generator, andpositive drivingpon- I 'nections between said motor and said-con'v 'pressor.

said generator, and an automatic voltage regulator for said generator. 6. In a motor truck-having a power plant adapted to drive the same, the combination of a refrigerating system in the truck, said system including a compressor, a direct current electric generator mounted on the chassis of the truck, positive driving connections 'between said generator and said power plant, an electric motor, "circuit connections for supplying said motor with current from said generator, an automaticvoltage regulator for said generator, driving connections between said motor and said compressor, said system being operable when the power plant of the truck is idle.

7. In a motor truck having a power plant adapted to drive the same, the combination of a refrigerating system mounted in the truck and including a compressor, an electric generator driven from said power plant, an electric motor, driving connections between said motor and said compressor, circuit connections for supplying said motor with cur rent from said generator, and automatic means for maintaining the speed of the compressor within relatively narrow limits notwithstanding wide variations inthe speed of said power plant. i

8. In a motor truck having a power plant adapted to drive the same, the combination of a truck body having a refrigerating compartment therein and a machine compartment arranged in the truck and separate from said refrigerating compartment, said machine compartment opening laterally at one side of the body, a refrigerating system ,in said body including a condenser located in said machine compartment and adjacent to saidoperiing, said system also including a fan and compressor in said machine compartment, an electric motor for driving said fan and compressor, an electric generator driven from said power plant, and circuit connections for supplying said motor with current from said generator.

9. In a motor truck having a power plant adapted to drive the same, the combination of a truck'body having a refrigerating compartment therein, a refrigerating system in said truck, said-system including an expansion coil in said compartment and a com.--.

pressor, a direct current electric generator mounted on said truck and driven from the power plant, an electric motor connected with said compressor to drive the same, circuit connections for supplying said motor with current from saidgenerator, an automatic voltage regulator for said generator,,a thermostat in said compartment, a solenoid in circuit with said thermostat, and a switch controlled by said solenoid for opening or closing the motor circuit.

10. In a motor truck having a power plant adapted to drive the same, the combination of coil in said compartment and a compressor,

a direct current electricgenerator mounted on said truck 1 and driven from the power plant, an electric motor connected with said compressor to drive the same, circuit connections for supplying said motor with current from said generator, an alternating current motor mounted'in said truck and connected with said compressor to drive the same when the power plant of the truck is idle, a thermostat in said compartment, and means whereby said thermostat is enabled to control the operation of either of said motors automatically in response to changes in temperature in said refrigerating compartment.

11. In a motor truck having a power plant adapted to drive, the same, the combination of a refrigerating system-mounted in the truck and including a compressor, an electric generator. driven from said power plant, an electric motor connected with said compressor to drive the same,circuit-connections for supplying said motor with current from said generator, automatic means for maintaining the speed of the compressor within relatively narrow limits notwithstanding wide variations in the speed of said power plant, and connections. whereby said motor may be driven from an additional source of power.

12. In a motor truck having a power plant adapted to drive the same, the combination of a refrigerating system mounted in the truck and including a compressor, an electricgenerator driven from said power plant, an electricmotor, driving connections between said motor and said compressor, circuit connections for supplying said motor with current -from' said generator, an automaticvoltage regulator for said generator, and means whereby said compressor may be operated from a source of electricity other than said generator.

13. In a motor truck having a power plant adapted to drive the same, the combination of a refrigerating system mounted in the truck and including a compressor, an electric 'generator driven from said power plant, an electric motor connected with said compressor to drive the same, circuit connections for sup- 1 plying said motor with current from said gension coil in said compartment and a compressor, a direct current electric generator mounted on the truck and driven from said power plant, an electric motor connected with said compressor to drive the same, circuit connections for supplying said motor with current from said generator, an automatic voltage regulator for said generator, and

means for automatically controlling said motor in accordance with the requirements of said refrigerating s stem.

BERT 0. SMITH. 

